Is there any difference in pulmonary testing parameters due to spirometry reference values? A study in adolescents with idiopathic scoliosis.

The Global Lung Function Initiative (GLI 2012) presented multi-ethnic spirometry reference values that are recommended to be used instead previous Zapletals' reference values. The study aimed to compare the values of the pulmonary parameters calculated according to the Zapletals' versus the GLI 2012 reference values in adolescents with idiopathic scoliosis. Preoperative pulmonary testing and radiographic evaluation were performed in 39 adolescents (29 females, 10 males) aged 12-17 years. The thoracic Cobb angle ranged 50°-104°. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured. The percentages of predicted values of FVC (%FVC) and the FEV1 (%FEV1) were calculated according to the Zapletals' reference values and to the GLI 2012 reference values. The subgroup analysis was performed for the subjects with Cobb curve 50°-74° (N=26) versus the subjects with Cobb curve 75°-104° (N=13). Mean %FVC was significantly higher using the Zapletals' reference values 86.1%±16.4 versus 84.6%±15.6 using the GLI 2012 reference values, p=0.0116. Mean %FEV1 was significantly higher using the Zapletals' reference values 84.5%±18.2 versus 80.0%±16.3 using GLI 2012 reference values, p=0.000001. The subgroup analysis revealed significant difference of %FVC in moderate (p=0.033974) and no difference in severe curves (p=0.1993). The %FEV1 differences were significant in both moderate (p=0.000011) and severe curves (p=0.0334). The study demonstrated that a significant difference might be observed in the spirometry parameters due to the applied reference values. These differences might be taken into account during the spirometry examination interpretation.

Loss of body height due to severe thoracic curvature does impact pulmonary testing results in adolescents with idiopathic scoliosis.

A standing body height is a variable used to calculate pulmonary parameters during spirometry examination. In adolescents with idiopathic scoliosis, the loss of the body height is observed, and it may potentially influence the results of pulmonary testing. The study aimed to analyze pulmonary parameters in adolescents with idiopathic scoliosis in relation to the measured versus the corrected body height. Preoperative pulmonary testing and radiographic evaluation were performed in 39 children (29 females, 10 males) aged 12-17 years. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured. The single best effort was analyzed. Thoracic Cobb angle ranged 50°-104°. Corrected body height was calculated according to the Stokes' formula. The subgroup analysis was performed for the subjects with curves 50°-74° (N=26) versus 75°-104° curves (N=13). Mean measured body height was 166.1±9.0 cm versus 168.9±8.9 cm mean corrected body height. The %FVC obtained for the measured height was significantly higher than obtained for the corrected height: 84.6% ±15.6 vs. 81.6% ±15.6, p<0.001. The %FEV1 obtained for the measured height was significantly higher than obtained for the corrected height: 79.8% ±16.3 vs. 77.35% ±15.9, p<0.001. The subgroup analysis revealed significant differences in %FVC and %FEV1 calculated for the measured versus the corrected body height, p<0.001. Corrected body height significantly influences the results of pulmonary parameters measurement. In consequence, it may influence the analysis of the pulmonary status of children with idiopathic scoliosis.